Exciting new opportunities to lie in the gutter and look up at the stars

The Guardian today joins the campaign to have street lights turned off or dimmed, on grounds of...well, the motives seem confused but it's something to do with councils needing to save money, something to do with an unquantified hope that turning lights off is better for the environment and mostly so that we can see the stars and not confuse migratory birds and insects. "We should not", concludes the crusading editorial, "be afraid of the dark". 

Except that, especially if we live in cities, perhaps we should be afraid of the dark, because many studies show a direct correlation between street lighting and crime.

Of course, its's far more complicated than that. Some studies have shown that street lighting reduces crime. Here's one (pdf) carried out by Cambridge University's Institute of Criminology in Stoke on Trent, which firmly "concluded that the improved street lighting caused a substantial decrease in crime". By contrast, some studies have shown either no effect or the opposite, that increased street lighting sometimes actually increases crime. Here's one from Chicago (pdf) in which it seems that illuminating the city's alleyways correlated with a significant increase in crime. 

An important factor may be the intensity of street lighting, with some studies claiming that harsh floodlights in particular increase the fear of crime; and entertainingly even the colour seems potentially important, with examples from both Japan and Scotland suggesting that blue lights reduce not only crime but also suicides.

There are also numerous anecdotes about specific lighting displays, for example at Xmas, attracting visitors and leading to temporary increases in crime, which people in favour of turning off the lights sometimes hold up, disingenuously, as evidence that public lighting has been generally shown to increase crime.

The British Astronomical Association's "Campaign for Dark Skies" is somewhat helpful in gathering together examples from both sides of the debate here, although the sample includes seemingly thorough academic studies, news articles and largely meaningless anecdotes on the same page and is of course intended to promote the anti street light agenda of the Association. Finally here's an attempt made by the Home Office (also pdf, sorry) from 2003 to pull together the then-existing data, that concludes "especially if well targeted to a high-crime area, improved street lighting can be a feasible, inexpensive and effective method of reducing crime." Unfortunately the Home Office report was effectively demolished for a series of statistical and methodological errors, most notably by statisticians at Leeds Met, leaving us still in the dark as to what we should make of multiple studies, multiple news stories, multiple theories and multiple agenda on the same topic reaching diametrically opposed conclusions.  

It seems obvious that some people are pursuing an agenda to have street lights turned off or down. Some appear to believe it will save money. It might save money, but of course crime occasions considerable public expense so it might not (and some who have chosen to go down this route have even gone to the lengths of denying the existence of any dissenting report - here's a town in Pennsylvania claiming, in cheerful defiance of the facts, that "none of the studies make a direct correlation between increased street lighting and reduced crime"). Some appear to believe it will help the environment, and that case seems unarguable - all other things being equal, wasting less energy is a good thing. Some others simply wish to have a better view of the stars, and again there seems no good reason to thwart that charming ambition provided it does no other harm. But given the current state of the evidence, it is merely willful ignorance to claim that turning off streetlights does no harm. The best we appear to be able to say at the moment is that sometimes it does, and sometimes it doesn't.

(Photo from Dean Lehman on Picasa)